Automatic telephone-exchange system.



P. SOHOENWOLF.

AUTOMATIO- TELEPHONE-EXCHANGE SYSTEM.

APPLICATION FILED APR.15, 1908.

Patented Sept. 15, 1914.

3 SHBETSSHEET l.

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P. SGHOENWOLP.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APBL-lUATION FILED APR.15, 1908.

8 SHBETSSHEET Z.

Patented. Sept. 15, 1914.

P. SOHOENWOLP.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR.15, 190B.

Patented Sept. 15,1914

8' SHEE '1 S SHEET 3.

if imme/Mo? F. SGHOENWOLF.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR.1G. 908' 1, 1 1 0,466. Patented Sept. 15, 1914.

@mmim v F. SGHOENWOLF. I AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 15, 1908,

Patented Sept. 15, 1914.

8 SHEETSSHEET 5.-

t P. SGHOENWOLF. AUTOMATIC TELEPHONE EXCHANGE SYSTEM APPLICATION FILED APR. 15, 1908. I 1,1 1 0,460, Patented Sept. 15, 1914.

B 8HEETS-SHEET 6.

F. SGHOENWOLF AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 15, 1908. 1,1 18,460; Patented Sept. 15, 1914.

B SHEETSSHBET 7.

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P. SGHOENWOLF. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR.15, 1908.v 1, 1 10,460.

Patented Sept. 15, 1914.

8 SHEETSSHEET 8.

9 .JZ m' connectors in all; The one/ hundred Eonnectors for the ten one hundred line groups constituting the first thousand lines of the exchange will have their contacts 201, 203, 205 multipled at the banks of the second selectors G assigned for that thousand, and

the multiple contact sets of the ten connectors for the. first hundred of the first I thousand will constitute the first group of ten contacts of each second selector for that thousand; the contacts for the connectors for the second hundred of the first thousand y will constitute the second group of contacts ofthe second selectors for that thousand, and so on for the'othcr groups for the first thousand. "Corresponding connections will be made from the difierent groups of ten connectors of the hundreds of the other thousands to the second selectors assigned to those thousands. On the usual ten per cent. trunking basis, there wi1l, of course, be one hundred second selectors G for each thousand .of the exchange and the contacts of the connectors will -therefore, if uniform multipling be observed, be multipled one hundred times, once at each second selectorfor the respective thousand.

Each second selector G is provided with multiple contacts 147, 149, 151 appearing in the banks of first selectors F, which first selectors are, of course, common for connection with all subscribers in the exchange. Ona ten per cent. basis there would be ong thousand first selectors F and each such first selector would have before its wipers 146, 148, 150, ten groups of multiple contacts, the

contacts of each group being connected to the second selectors G for a different thousand There being one thousand first selectors F an one thousand second selectors G, there will e a total of one hundred thousand multiple contact sets 147, 149, 151, at the first selectors, so that each second selec'tor G will have its contacts multipled only at one-tenth-of the first selectors F in the usual course of multipling.

V Each first selector F has permanently joined to it'a line selector E before whose wipers 63, 64, 65, appear multiple contact sets 18, .71, 72, of one hundred lines, which sets; of,contacts may be called multiple calling contacts. The lines of the exchange as calling. lines are divided .into groups of signed to that group of lines as calling lines. Further, the multiple contact sets of each so,

one hundred and on a ten per cent. basis, the

multiple calling contacts of each one hundred line group will be multipled before the wipers 53, 64, 65, of ten line selectors asindividual multiple contacts of the calling nector out of such group; whereafter the selected connector will be adjusted to pick out the required group of lines and then the required line out ofsuch group.

In the dia ram, Fig. 1, part 1, I have illustrated a cal ing substation A connected by the line conductors 32 and 33 with a suitable line circuit arrangement at the exchange. The substation at A includes the customary hook switch 25, normally holding the calland, adapted, onthe removal of the receiver, to be lifted, disconnecting the call-bell and operatively connecting the talking set with the line. A calling device or dial 30 is provided, said calling, device being normally locked by a pivoted pawl 27 controlled by the magnet 26 whose winding also. serves as the impedance coil for the talking set. Nhen the coil of 26 is energized; its armature is attracted and the pawl .27 withdrawn from engagement with the dial 30 so that the same may be rotated by hand in the direction of the arrow. The dial 30 has attached to it suitable teeth of insulating material which control the connections of the impulse springs 28 and 31, and the said dial also carries upon its lower part a stud of insulating material, which, when the dial is at normal,

as shown, holds the spring 29 disengaged from its associated spring. When the dial is rotated by hand in the direction of the arrow, the said stud frees spring 29 which, by its tension, engages its contact and makes connection with round. When released, the dial rotates bac to normal and when it .bell in an operative bridge of the line limbs reaches this point, the said stud restores spring 29 to its normal relation shown. It is obvious that the-rotation of dial 30 in'the direction of the arrow has no operative efiect upon the springs 28 and 31. When, however, it is released, the teeth of insulating material operate to momentarily open contact 28 as many times as there have been teeth brought below said spring. After the last tooth passes above spring 28, the tooth at the extreme left causes a momentary opening of contact31 whereai'ter the calling device reaches normal and its motionis arrested. While the openings of circuit were being made at contact 28 in the line limb 33, it is apparent that line limb 32 will be connected through contact 31 to ground through the tion. It is thus apparent that by the operation of the dial 30, a calling su criber can cause a number of sets of openings of line limb 33 at; contact 28, while line limb 32 continues grounded, each set of openings of line limb 33 being necessarily followed by one opening of line limb 32, while limb 33 remains grounded. By successive actuations of the dial30, the calling subscriber is enabled to count out the' digits. comprising the I number of the called subscriber and the various openings of lineilimbs 33 and 32 cooperate with the directively operable switches at the exchange in completing the connection with the called-for line.

As before indicated, the lines as calling lines, are divided into groups of one hundred by having their multiple contacts grouped at the exchange before the line selectors. The ten line selectors E for each such group of one hundred lines are preferably not constantly operating devices, but are normally at rest, their wipers having a fixed or normal position. For starting an idle line selector E when 'a call is ini-. tiated, a master-switch mechanism D is provided, one for the one hundred lines, including wipers 52, 53, having before them contacts 54,55, one such set being provided for each of the ten line selectors of a one hundred line group. Each line of a group has its line relay 42; and a coinmonconductor 44 is provided, connected to the masterswitch relay it and having branches, one to g each of the line relays of the one hundred lines whereby any calling line of the one *hundredmay control the master-switch D to start an idle line selector. Each line, in addition 'to its line relay 42 individual to it, has its cut-oft relay 37 the latter being eniployed. to render the line relay inoperative when the line is connected with.

As before indicated, the multiple contacts 18,71, 72, of the one hundred lines of a group of calling lines, are divided into ten groups of ten contact sets each at the line selector banks, whereby the one hundred lines are divided into ten sub-groups of ten lines each. Each such sub-group has a subgroup relay 42 42", etc., and a sub-group contact 73,73 etc, appearing before the group selecting wipers 66 of the line selectors The group relay 42, of each sub-' group has an; armature .43 controlling theelectrical condition of the group contact 73. Each such group relay 42 42", etc., is conten branches. one extending to each line relay of its sub-group, so that the line relay of any line of a sub-group can control the respective group-relay.

The constantly rotating common interrupter I is provided, having two contact springs 57 and 58 and a cam projection which latter, as the interrupter travels, closes in rapid succession the springs 57 and 58 alternately to their associated contacts. The spring 58 is connected to a comn'idn conductor having branches 111 extending to armatures 80 of the relays PR of the different line selectors E and the interrupter I -is employed among other uses to transmit currents over the branches 111 to operate the windings 10 ofthe driving magnets 10 to produce the long step travel of'the line sobeing actuated by a partial impulse over a might be produced, the circuit at each switch E is so arranged that its relay PR atcd only by current through spring '57. By this arrangement no current can flow through a winding 10 when relay 42 of a calling line and common relay 44- are actuatcd until after contact 57 has been closed to operate the relay of the line selector E to be started. Thus the interrupter I by its alternating circuit closingfu'nction precircu'it ofrnagnet'lO and the transmission of actuating current over the saidcircuit.

Before going more specifically into the description of the circuit diagram, the .pre-

ferred. mechanical arrangement of the switchwi-llbe referred to. As indicated in Fig. 4, ten groups, of ten contacts each, .18, 18, 18 etc., to 18 are provided arranged in a circle, making one hundred of such contacts, while between the groups of contacts 18, contacts 19, 19, 19?, etc., to 19 suitably journaled, as indicated in Fig. 5, to the circular base plate 8* and to ,the bridge 8 upon which shaft are mounted the wipers m, n, 0, p, s, and the ratchet wheel 20 which of course has one hundred and ten ratchet teeth. The magnet 10, whose spools are mounted upon the bridge 8, haspiece extends a slottedrstud 23 with which is associated the friction piece 23*"ai1d the screw 25 threaded to the piece 23", thewhole furnishing a convenient meansfor adjust ing, the tension of the spiral spring 21; one end of which is attached to the end of the armature 3 apd the other to the stud 23.

branch 111, whereby but a partial longstep controlling the-long step travel, can be actuserves a proper sequence of operation be-. tween the closing of a contact (80) in the are located. A. rotary shaft 1 is provided a pole piece 24 connecting the upperex 'treinities of the cores, and through thispole nected bya common conductor 42 having lee-tors E. To prevent 'a winding 10 from tion of the magnet 10, being adjustableas described. The core of each spool of magnet 10 has, at its end adjacent to bridge 8, a pole piece of the shape indicated at 9, the transversely disposed armature?) having the projections shown best in Fig. 4, extending to proximity with the respective concave surfacesof the pole pieces 9, the whole 'producing an arrangement well calculated to give a strong initial pull upon the armaturev 3 when magnet 10 is operated, permitting along with this, a relatively great movement of the said armature, an adjustable stop 4 is provided to limit the back stroke of the armature away from the pole piece. The arm 6 carrying the driving pawl 6, which is provided with a suitable spring to hold it in engagement with the ratchet as indicated in Fig. 6, is fastened to the armature shaft 1 so as to partake/of the rocking movements of the armature, the pawl 6 being by them eiiective to drive the ratchet wheel 20 step-by-step. The adjustable stop 12 is provided threaded to a projection 'of the piece 13 which is fastened by the bolts 15, 16 to the circular bank of the switch, and the said stop serves to limit the length of the stroke of the pawl 6 and of the armature 3 when long step trave. The piece 13 also has a pro3ection to which is suitably pivoted the pawl 7 which engaged the teeth of the ratchet 20 and serves to prevent back movement of the ratchet which might otherwise occasionally occurflfrom the jar occasioned by the armature 3 when forcibly retracted by the spring 21 at the conclusion of one, of its long strokes. The pawl 7 carries a pin engaged by the arm 6 so that when the latter is fully retracted, the two interlock and the pawl 7 is foncibly held in engagement with the ratchet 20. A further important function of this arrangement is to render im possible a between-contact position of the wipers. Thus, if the pawl 7 is, at the time pawl 6 is retracted, not engaging a full tooth of'r'itchet 20, the impact of arm 6 will force the pawl 7 to fill the tooth upon whose surface it rests, whereby the wipers will be carried back to one of their definite operative positions. Upon the piece 13 is mounted the stop magnet 14, controlling the stop pawl 5 forming its armature; in Fig. 5 it is shown below the pawl 6*; being therefore normally out of engaging relation therewith. The said stop pawl 5 abuts upon the projection 17 of the piece 13 and when the magnet 14 is energized, is brought for ward so that its upper extremity'is' in the path oi the pawl 6, thus limiting the'stroke The switch is performing its selector F with such line.

of armature 0, piece 6, and pawl 6. It is now apparent t at when magnet 14 is deener zed, actuations of the magnet will, by paw 6, produce long steps ofthe switch wipers, and for each such long step, it will be understood that the wipers will be moved from a position engaging a between-group contact 19 over an entire group of contacts 18 to engagement with the next between group contact 19.; Thus, to select the group of contacts 18, for instance, three actuations of the magnet 10 will be produced while magnet 14 remains inert and the wiper m and the others-will then have advanced three long steps to rest in a position where wiper 12?, engages the contact 19. When, now, magnet 14 is energized; the movable stop 5 is substituted for the stationary stop 12 as the memberlimiting the stroke of the armature of the magnet 10, and successive actuations of magnet 10 will now obviously produce short steps of the wipers, each step 'moving them the space from one contact 18 to another. When the switch 015 Fig. 4 is to be restored to normal, this is effected by short step travel of the switch around in the initial direction of travel to the normal point to complete a circle of travel.

Switches similar in mechanical construction to that shown in Figs. 4 to 6 are also employed for the first selectors F, second selectors G and connectors H, the contact arrangements for wiper contacts and offnormals being of course provided in the circuit drawings. 7

The remaining features of the circuit conmechanical structures to correspond with the nections will best be understood when given in connection with the narrative of opera: tion. Let it be assumed that the calling subscriber A desires his line to be connected for conversation with that of the called subscriber whose substation is indicated at K and whose directory number will, for the purposes of description, be assumed to be 1112.

The calling subscriber at Aremoveshis receiver and an idle lineselector E is set in travel and immediately picks out the calling line, thereby connecting the paired first The wipers of the line selector normally rest between the tenth and first contact groups. line A, as indicated by multiple contacts 18, 71, 72 and the roup ,contact 73", is included in the seconr? subgroup of lines, so that one long step of the wipers of the line selector will be required to hring them adjacent to this group of contac s.

By the removal of the receiver at A, current flows from ground, through line relay 42, armature 36, wire 82, contagt 31, magnet 26, the raised hook-lever 25, returning through the transmitter at thepubstation,

The calling the position of its" circuited and the flow of current reduced to a point where magnet 26 releases its armature to again lock the calling device 30.

Armature 41 now removes ground from the multiple contacts 18 of the calling line, rendering them selectable, and also energizes the group relay 12 'whereby armature 43 leaves its contact, ungrounding the multiple group contacts 73 of the second sub-group at. the line selectors and rendering them selectable. The armature 88 disconnects the cut-off relay 37 from themultiple called contacts 1-6 of the calling line and connects battery B to said contacts through the protective resistance 7', whereby the multiple contacts 46, 47, 48 at the connectors are rendered busy against incoming calls. Armature 40 operates the master-switch relay 44, whose attracted armature 45 closes a circuit to the wiper 53 of the master-switch D, each line selector E assigned for a group of one hundred lines having contacts .54, 55 before the wipers 52,53 of the masterswitch serving-the corresponding line group, and the said wipers 52, 53 normally resting engaging the contacts 54, 55 of an idle line selector E. 1

If at the time the relay/14 operates, the cam projection of interrupter I is engaging the contact spring 58 and so holding its contact closed, the lnitiation of travel of line selector E will be delayed until. the said cam projection rotates free of spring 58 and comes aroundto closed contact at 57. This delay is caused because relay PR, controlling the long-step travel of the switch, can only be operated to close its contact and so connect spring 58 with the longstep wind: ing 10 of magnet 10 by'current through contact 57. The circuit for relay PR is closed from ground at switch D, through normal. contact51, contact 57 when interrupter I closes the same, attracted armature 45, contact 5355., off-normal contact 69--70, relay PR- towbatte ryfB. Relay PR for a mo ire nt locks "to -gr o'undada-armature 81, wiper66 and contact 73 01 the first sub-, group, said cohtact being grounded because no line in that sub-group is calling. Armature 82 of relay PR operates relay 85 which, by armature 86, locks to ground via normal contact 9.4 of release relay RR. Armature 83 closes a circuit from ground through contact 83- -84, normal contact 97 and secondary relay SR to battery. As interrupter I continues to travel, it closes Contact 58, whereupon circuit may be traced from ground through the branch wire 111, closed contact 80, long-step winding 10' to battery B. Stop magnet 14 being inert at this time, a long step of the switch wipers is produced, moving them from position between the tenth and first contact groups to positions between the first and second contact groups. lVhile this long-step is being made, the relay lR will continue operated by ground through armature 81, wiper 66 and the grounded segment 74, the off-normal contact G9, 70 having been opened on the initiation of the long step, and the initial energizing circuit of relay PR thereby destroyed. \Vhen the switch Wipers complete the step, wiper 66 will be ungrounded at contact 73 of the first sub-group, the relay 42 having been operated as described, and relay PR will become deenergized and circuit connections shifted to produce short-step travel of the line selector in search of'the individual contacts of the calling line.

By the retraction of armature 83 to engage its normal contact, a-circuit is closed from ground through attracted armature 88 and the relay 89 to battery, which relay, by armature 91, locks to ground through off-normal contact G8, 6?, closed on the initiation of travel of the switch. By the make-before-break arrangement atcontact 84, relay SR has its circuit continued through normal contact 84:, alternate contact 101, and wiper 63 engaging the grounded between-group contact 19, sothat relay SR at this time continues operated Circuit may now be traced from battery B through the stop magnet 14, attracted armatures 92, 103, and to ground through normal contact 83, whereby magnet 11 is actuated and attracts its armature 5, constituting the stroke-limiting stop for the driving magnet 10. The impulses will now flow from genera torg through the short-step winding 10 of magnet 10, contact 5, attracted armature 102 to ground, winding 10 now producing short steps of the wipers of the line selectors E, moving them step by step in search of the individual multiple contacts of the calling line. Relay SR controls the circuits of winding 10 and of magnet 14, and said relay will continue operated by current flowing. through its winding over a beforetraced circuit to wiper 63 and to successive contacts 18 of non-calling lines, such contacts being grounded through the normal contacts 35 land 11 of their respective line circuits. When, however, wiper 63 engages the contact 18 of the calling line, such contact will be ungrounded because of the attraction of armature 41 of the line relay 42,

relay SR will deenergizc, opening the circuit of winding 10 at armature 102 and that of magnet 14 at armature 103, shortstep travel of the switch then' of course ceasing and the wipers '63, 64, 65 remain engaging the multiple contacts 18, 71* and response to the operation of relay PR as described, armatures 99 and 104 placed the line wipers 64, 65 on open circuit. Armatu re 104 further closed a circuit extending from the positive side of the battery B throu h relay SR over conductor 108, attracte armature-1 04, normal contact 98, conductor 107, relay PR to the negative side of battery A said batteries A and B being connected in series and grounded at their intermediate point. By this means the relays PR and SR were simultaneously operated to open the release contacts 114, 115 when the switch E started. When, now, relay SR denergizes, the circuit traced for relays-PR and SR no longer exists, but a new circuit for relay PR may be traced from battery A", conductor 107, contact 99, contact 64-41, normal contact 34*,

cut-oil relay 37 to ground, which relay opcrates and, by the closure of contacts 34 34 bridges the relays :PR' and SR directly across the limbs 33-, 32 of the calling line, the shifting of their circuits being thus accomplished without de'e'nergization of the relays. Armature 34 of relay 37 also disconnects the relays winding from contact 71*, but armature 35 has closed an alternate circuit for said relay 37 extending through contact 1863, normal contact 100, at tracted armature 90 to battery B, whereby the relayv 37 remains locked. The opening or the different line selectors. 55'

of contact 36 denergizes line relay 42, whercon the relays 44 and 42 are also deenergized.

Upon the actuation of the relay 37 and Lhe'closure of contact35, ground'through said relay is, over a circuit branching from the one previously traced and extending through normal contact 101, placed upon the contact 54 of the line selector E at masterswitch D. This causes the energization of the relay whose armature 51 c oses a circuit of motor-magnet M which, by a suitable pawl and ratchet, drives the wipers-52, 53 rotarily to sweep over the contacts 54, The said wipers have a continuous rotary direction, that is, without return movement, and the contacts 54, 55 are in practice arranged to form'a complete circle. As long as the wiper 52 sweeps over contacts 54 connected to line selectors E connected to calling lines therefore busy, the relay 50 will remain operated by current flowing to ground over the successive contacts 54, and pulsations from generatgr 9 will continue flowing through the mhgnet M. As soon, however,

. the driving magnet 10* of first selector F to nuance as wipers 52,53 engage contacts 54, 55 61;. an idle line selector E,'t he open circuit con-- dition of the contact 54 deenergizes the rela 50 whose armature/51 opens' the circuit 0 magnet M and the wipers 52, 53 remain engaging the contacts. of the idle line selector, ready to start the same when anew call is initiated.

It may be stated at this time that the-nor- 30 to open contact 28 once, thereby causing the line limb 33 to be opened and relay PR denergized a single tlme, while relaySR remains operated by current flowing to ground through contact 31 and contact 29; After this, of course, contact 3l wi1l, with: the return of dial 30 to normal, be opened to ,deenergize relay SR while relay PR will remain operated by current flowing through contacts 28, 29 to ground. The deenergizae tion of relay PR transmits a current impulse from ground through contacts 118, 116, 154 and the long-step winding 10 of battery, the actuation of said winding 10., producing a long step of the wipers 144, 146,-, 148, 150 and 152, causing them to move to a position between the tenth and first groups, of contacts. On the initiation of short-step travel of the first selector F, the said wipers will now move rotarily step by step over the contact sets constituting the first group, which contacts are multiple terminals of second selectors G assigned for connections to the first thousand ofthe exchange. It will. of course be understood that had the first digit of the called subscribers number been 5, the calling device 30 would have been actuated to produce five denergizations of relay PR, followed by one of relay,SR',-and' each deelnergization of relay PR would have produced a separate actuation of winding 10 and the wipers of the first selector F would have been advanced five long steps In the present case, after the singledeiinergization of relay PR whose results have been described, the de'elnergization ofarelag 20 contact-point b of the ring 153, contacts a, b, 125

0 and (l being placed between each contact group, through contact-171 and locking re.--

lay LR to battery, actuating the said relay, which, by armature 159, looks fol-5a moment to 'ground through the wiper 144 now en- 130.:

its

to select the fifth group of contacts, and so for the other thousands.

gaging the contact projection 7) of ring 145 adjacent to the first group of contacts. Armature 15S actuates busy relay BB whose armature 162 instantly energizes locking relay LE by current to ground at 174 which,

by armature 156, locks itself to ground at said contact 171, closed when the long step began. BB operates stop magnet 14 which throws in the stop pawl and closes contact 5, whereby generator circuit through winding 10 of magnet 10* is closed and the short-step travel of the switch initiated. At the first step, the opening of contact 144-145 at projection b deenergizes relay LR", so that relay BB now depends for its continued energization upon a circuit extending through attracted armature 161, contacts 163, 169, to wiper 146 and to grounds upon successive contacts 14:7 encountered by said wiper, the private contacts 117 of busy second selectors of the first group having been grounded by' other first selectors F having previously selected them.

In the present case. it is assumed that the.

second second selector (1 of the first group is idle and its contact 147 so ungrounded. 'hen, therefore. wipers 116, 148 and 150 engage contacts 117, 149. 151", connected to conductors 176. 17?, 17B, respectively, the wiper 146 will be ungrounded and busy relay BR will be consequently deenergized,

armature 160 de'energizing magnet 11 and the denergization of the latter opening the circuit of winding 10*, whereby travel of the first selector F stops with the wipers engaging the contacts specified: I

Circuit may now be traced from ground through normal contact 160 of relay BR through attracted armature 155, relay 175 to battery, which relay at once energizes, its armatures 167 and 172 closing circuit from condensers 112, 113, to the talking wipers 1 i8, 150 of the first selector; a clean circuit,

now existingto these points, \vinding10 being disconnected at contact 154 and contact 152-153 havingbeen opened on. the first short step of the first selector F. Ground upon the wiper 146 rendering 1uultiple contacts 147 of the second selector G busy,may now be traced through alternate contact 169, the winding of release relay RIF and through attracted armature 157..

Another branch of this circuit, which shortcircuits the relay RIP,- exists over the wire 1'10 andthiough normal contact 96 of release relay R at the line selector'E. The

calling subscriber A nowactuates his dial 30 to record the second digit of the called subscribers-number, the action resulting in a single deiinergization of relay PR followed bv one relay SR. resulting impulses being transmitted to the-second selector G to operate the same in a manner quitesimilar to that in which the first selector F operated.

The denergization of relay PR trans- Attracted armature 160 of relay lnits a current impulse from ground through contacts 118, 116, 167, 146-4619 over wire 177, contact 179, the long step winding 10 of magnet 10" to battery 13. The resulting actuation of magnet 10 steps the wipers 198, 200, 202, 20 1, 206 of second selector G over the entire tenth group of contacts to posi-, tions adjacent to their first group; wipers 200, 202, 204, being then adjacent to the eontacts 201, 203, 205, forming terminals of connectors assigned to the first hundred of the first thousand' At this time the wipers 198 and 206 will of course be engaging the corresponding contact projections b, b of the rings 199 and 207.

If the called line had been in the fifth hundred, the calling device- 30 would of course have been operated to produce five deenergizations of relay PR and the trans- 196, locking relay LE to battery B", which relay, by armature 1S1, locks itself to ground through contact 198190 at b. Armature 183 actuates the busy relay BR ,'which, by armature 1S7, closes a circuit from ground at contact 211, closed on initiation of travel of the switch G,'and through relay LR to battery, which relay by armature 181 locks itself to ground at contact 211. Relay BR, by closing alternate contact 185. actuates the stop magnet 14", throwing the stroke limiting stop in and armature 5* then closes generator circuit for the short step winding 10 of magnet 10". Short steps of the wipers of switch G will now of course he produced as long aswinding 10 and magnet 14 continue to receive current. On the first short step, contact 198-499 at b is opened and relay LR is denergized whereupon relay- BB depends for its continued energization on current through armature 186, contacts 188, 1.95, to Wiper 200 and to successive grounds encountered upon multiple contacts 201 pertaining to connectors H which have already been seized by some other second selector G and so grounded. In the present case, it is assumed that the second set of con tacts 201, 203, 205*, connected respectively to wires 208, 209, 210 are those of the idle connector HI l Vhen the wipers of switch G engage these contacts, contact 201 will be ungrounded, circuit through busy relay BR. will be opened and the relay denergized whereupon armature 185 deenergizes magnet 14, the latter, by armature then opening the circuit of winding whereby further short steps of switch G are prevented. The closing of alternate contact 185 completes the circuit traced through attracted armature 180 and relayl192 to battery B whereupon armatures 193and197 close conductors 177 and 178 to wipers 202, 204, now in contact with wires 209, 210 respectively. A clean circuit now exists through the second selector G to the connector H, the opening of contact 179 having disconnected the winding 10 from wire 17? alternate contact at 194 over wire 176, wiper 146, armature 168,.wire 110, and to ground through normal contact 96, at the line selector Contacts 201 of the selected connector H are thus made busy. The calling subscriber now actuates his dial to register the third digit of the called subscribers number, the operation of the dial causing a by ne of relay SR. The denergizationof relay PR transmits a current impulse from ground through contacts 118, 116, 167, 148 149*, 193,202203, wire 209, normal contacts 230 :nd 222, the current then branching, a pai t flowing upward through winding 10 of magnet 10 and to battery actuating said winding and producing a long step of the wipers 250, 251, 252 of the connector H causing them to advance over their tenth group of contact sets 46, 47,48, to positions adjacent to the first group of contact sets 46, 47, 48*, the same forming terminals of lines 1111 to 1119 inclusive, followed by the terminal of line 1110, the naught being represented by ten impulses. The remaining portion of the current transmitted overwire 209 flows through the off-normal contact 219 and through locking relay LR to bats ile deenergization of relay PR followed tery which relay at once locked by the 010- sure of contact 217 to ground at spring 232.

Had the called subscriber been in any other group at the connector H, say in the fifth group, the substation calling device would of course have been actuated to transmit five impulses over wire 209. The first of these would have produced the first long step of the switch wipers as just described, and have operated the locking relay LR. The remaining four impulses would have 7 passed in their ,entirety through the winding 10 of magnet 10", the ofl'normal contact 219 having been opened at the initiation of the first long step. In such case, the subsequent operations of the connector would be the same as those now to be described for selecting the line out of the first group.

ground through contacts 117, 119, 172, 150 151, wire 178, contacts 197, 204205, wire 210, alternate contact 216, normal contact 221, locking relay LR to battery, said relay, by armature 228, locking itself to ground at contact 232. Armature 229 of relay LR operates the relay LR which, by armature 222 looks to ground via the closed oit-normal contact 225. Armature 224 of the latter now energizes the stop magnet 14, via contact 236, which throws in the stroke limiting stop and the connector H is -ready for its short step travel. The calling subscriber A now actuates his dial 30 to produce two I deenergizations of relay PR and each transmits a current impulse over the before traced path to wire 209, the current now flowing through alternate contacts 230, 222,

winding 10* to battery B and two short steps of wipers 250, 251, 252 are thereby produced bringing them to engage the multiple contacts 46, 47, 48, of the called subscribers line K, #1112.

Following the impulse over wire 209, a deenergization of relay SR transmits a final impulse over wire 210 for the purpose of causing a test of the called-for subscribers line to determine its idle or busy condition. I This impulse of current flows through alternate contacts 216, 221, 227, lower winding of test relay TR to battery which relay is lmmediately energized. Its armature 231, by engaging contact 233, connects its upper winding through contact 237, with the test wiper 250, contact 232 at relay TR being thereon opened and locking relays LR and LR deiinergized. Assuming first that the called line is idle, the condition illustrated at K, the, multiple contacts 46 will be connected to ground through cutoff relay 37. Under these circumstances, the upper winding of relay TR being also grounded, said relay TR deenergizes as soon as the impulse over wire 210 is disconnected from the lower winding, and the armatures 231 and 234 of relay TR are retracted. A circuit may now be traced from'battery B through the relay 212 through contact 220, normal contacts 226, 231, 237, contact 25046, normal contact 38 of line K through cut-off relay 37 to ground whereby relays 212 and 37 are energized. By'the operation of relay 37, the line relay 42 is cut-off from the called line, ground through armature 35 is placed on the multiple contacts 18 at the line selectors to hold them busy and the closure of contact 34 connects the line wire 33 with the multiple contact 47, thus completing the talking circuit to the connector.

On the operation of relay 212, the closing 1,1 m ss of contact 239 connects the constantly op erating interrupter l with the ringing or generator relay (11R and said relay is, with the travel of said interrupter, alternatelj. energizedand denergized, connecting and disconnecting the generator '9 from the called line to periodically ring the substa- ,tion bell. The path for generator current includes contact 251-47, 34 34, contact 28. the bell and the depressed hook lever at the substation K, the condenser, contact 31, wire 32, contact 48, 252, and through induct-ance 253, to ground through battery B \Vhenever the armature ofrelay GR is retracted, the relay 213 is, via attracted armature 240 of relay 212, connected with the wiper 251 and contact 47. \Vhen the called subscriber answers the call by removing his receiver, the closing of the alternate contacts will, as soon as the armature of relay GR is retract-ed, close a circuit including the relay 213 and the line limb 33, the transmitter and impedance 26 at the substation, the limb 32, contact 49 252, inductance 253 to battery 13*. This flow of current of course energizes the relay 213 and furthermore supplies energy for the substation transmitter at K for talking purposes. The closing of contact at 242 operates the relay 214 by current therethrough and through closed contact 241, said relay 214 by armaturev 247 locking itself over a branch through armature 247. Armature 246 opens circuit for relay GR so that the same remains inert with its armature retracted and generator 9 excluded from the called line. Armatures 245 and 249 now complete the talking circuit through the connector H.

The calling subscriber A and the called- :tor subscriber K are now ready for conversation, the talking circuit throughoutthe exchange and over the telephone lines being indicated by the heavily marked conductors. The supply of current forthe calling subscribcrs line is fed from the serially connected batteries A and B through the impedances of relays PR and SR, the condensers 112 and 113 being interposed between the battery connect'ons for the two substations so that each receives its supply oi current independently of the other.

When the two subscribers have completed their conversation they replace their receivers. The act of the called-for subscriber K restores the connector H to normal and the act of the calling subscriber A restores to normal the line selector 1*], the first selector F and the second selector G.

The replacing of the receiver at the called substation of course opens the circuit of the relay 213, and on its deiincrgization, current will flow from battery B through the lower winding of release relay llR normal contact 243, contact 248 and through contact to ground. Release relay lilt thereon energizes and attracts its armatures whereof 238 looks the said relay to ground at contact 223, armature-235 closes the circuit of stop magnet 14, throwing the stop in, whereon circuit may ,1 be traced from generator through winding 10 closed contacts 5, alternatecontact 2236, contact 224 to ground. Short-step travel of the connector H will now necessarily take place turning the wipers around in the original direction of travel until they reach normal. At this time oilnormal contact will be opened, relay LR will decnergize and the opening of contacts 223, 224, will deenergize relay RR" and winding 10 of magnet 10 respectively, the switch wipers then stopping at normal. As soon as wiper 250 leaves contact 46 the circuit through relays 2 12 and 37 is open and by the resulting opening of contact 241, the relay 214 is deenergized and its armatures retracted. During the restoration of the connector H, a ground upon the multiple contacts 201 has been'retained over wire 208 through normal contact 244, the upper winding of release relay RR and to ground through attracted armature 223 of relay LR", whereby the connector is held busy until it has fully restored and improper selection prevented. I

When the calling subscriber replaces his receiver, the opening of the conductive circuit through the substation deenergizes for the first time simultaneously the relays-P43 and SR, and the simultaneous closing of contacts 114, 115, completes a circuit exteud ing from battery B at line selector E through the release relay RR over wire 106, returning over wire 109 and through at tracted armature 93 of relay 89 toground, whereupon relay RR locks itself by armature 95 to ground at armature 93. By armature 9G, ground is removed from conductor 110 and battery connected thereto from B, through attracted armature 90 of relay S9 and current flows over the wire 110, through alternate contacts 168, 169- at F and through release relay HR to ground at attracted armature 157, whereupon release relay RR locks itself from battery by its armature 164. The battery current over wire 110 passes in part through contact 146, 147 over wire 176 through alternate contacts 194, 195, release relay RR at second selector G and to ground through attracted armature 182 of relay LR, relay then locking itself from battery B by armature 189. a,

The release relays RR of switch E, R 13 of switch 1 and RR of switch (it are now all energized and cause the restorations of their respective switches independently of each other.

.Referring first to the line selector E, armature 97 of relay RR energizes secondary relay SR, whereupon circuit is closed from battery through the stop magnet 14, at

30 5 is attracted to the in tracted armatures92 and 103 and through normal contact 83 to ground. By the actuation' of magnet 14, the stop is thrown in and circuit closed from venerator 9, through 5 the short-step winding 10 contact 5 and contact 102to ground. Short steps of the line selector E will now be produced until the wipers 63, 64, 65, 66 complete a revolution around to normal, when the opening of contact 6768 de'c nergizes relay 89, whose armature 93 deenergizes relay RR which, by armature 97, in turn denergizes relay SR. Retraeted armature 92- of relay 89 opened the circuit of stop magnet 14, and the resulting opening at contact 5 prevented further actuations of winding and the continuing of the wipers at rest. The mechanism of the line selector E is now at normal, the relay 85 havingbeen deenergized 0 when release relay RR first attracted its armature 94.

When relay RR at first selector F energized, its armature 166 operated busy relay BB by current to ground through off-nor- 5 mal contact 174. Attracted armature 160 of relay BR denergized relay 175 so that wipers 148, 150, were on open circuit during restoration and said armature 160 also ener- 4 gized the stop magnet 1 1 whose armature position, also closing the generator circuit for winding 10* of magnet 10; Short-step travel of the wipers of the first selector F will now be produced. until they have completed a revo- 5 lution around to normal. At this time the opening of ofi'-nor,mal contact 17% decnergizes relays BR and LR. The opening of contact 157 deenergizes release relay RR 'while the retraction of armature 160 015 re-- layBR opens the' circuit of magnet 14,

'50 165 maintained the required Bl) cuit for the short-step whose retracted armature 5 prevents further actuations of winding 10 and first selector is at normal.

The Contact 54 of the switch pair EF at 5 the master-switch D was held grounded until both switches E and F were fully restored. At line selector E, ground was maintained through attracted armature 94, and at first selector F attracted armature ground until the switch reached normal. When release relay BB G energized, its armature relay BR by current to 5 off-normal contact 211.

relay BR opened the circuit of relay 192, and said armature 185, in engaging its alter-v nate contact, operated the stop magnet 14 which in turn closed, at contact 5", the cirwinding 10.- The wipers of switch G now travel by short steps around to normal at which time contact 211 is opened, deenergizingrelays LR and BB The opening of contact 182 denergizcs reof second selector 191 operated busy ground at closed Armature 185 of contacts 200, 201,

lease lease rela R11 The opening of contact 185 of re ay BB deenergizes stop magnet 14", whose armature 5" opens the circuit of winding 10 and. the switch wipers rest at normal. During the restoration of ,second selector G, the multiple contacts 1 1'? at the first selector F are held grounded and so busy by attracted armature 190 of. release relay RR circuit being traced through normal contact at 194.

Let it now be assumed that the called line K was busy at the time the last impulse was transmitted over wire 210, through alternatc contacts 216, 221, 227, and the lower The called line winding of test relay TR. being busy, its multiple contacts 40 will be connected to battery in one of three ways. First, if the called subscriber K had removed his receiver and his line had not yet been selected, the contacts 46 would be connected to battery through alternate contact 38. If the line K had been a calling line and had been selected said contact 46 would be connected to battery (see switch E),tl1rough attracted armature 90, normal contact 100, wiper 63 of a line selector in connection with the line, through its contact 18, and through attracted armature 35 and retracted armature 38. If the called line were busy because some other connector H had already selected the line, the multiple contacts 16 would have battery upon them through wiper 250 of such other connector H having already seized-the line.

In any of these cases, the closure of contact 231-233 would permit the flow of current from battery at the multiple contact 46, over wiper 250, normal contact 237, contact 231233 and through the upper winding of test relay TR to ground, said relay therefore continuing energized. Since armature 234 remains attracted, the busy tone from interrupter 1* will be transmitted through normal contact 216 to wire 210, over the lower talking conductor, through the exchange and through the telephone at the calling substation A, returning over the upper talking conductor and through the winding of relay PR at the first selector F. The calling subscriber, being Ihus advised that the called line is busy, replaces his receiver, and switches E, F and G restore to normal as before. Under the present circumstances, the replacing of the receiver at the calling substation also restores to normal switch H. This is effected by the restoring battery impulse, passing over wire 17 6, finding its way through attracted armature 194, conductor 208, normal contact 244, the winding of. release relay RR to ground at contact 223. The said rerelay is thereupon energized and locked over the previously described path to ground at contact 223 of relay LR. The stop magby a line selector E,

the

1,11o,4.eo

net 14 is now energized resulting in the restoration of the wipers of switch A as previously described.

Referring to the line selector E, Fig. 1, part 11, an"e special feature of operation is employed when the line selector is to select a calling line in the sub-group immediately adjacent to the normal position of the wipers 63, 64-, 65, 66. The group relay 42 for this sub-group is shown, having the armature an controlling the grounded condition of the multiple group contacts 73 for the subgroup. When. a linein this sub-group initiates a call, the group relay @2 will of course be operated in a manner similar to that in which the group relay 412 of the subgroup of A was operated, ground being re moved from the contact 73. When interrupt'er l: closes contact 57 be operated to energize the relay 85 which by armature 86, locks to ground at nor-ma contact 94, With the travel of interrupter I, relay PR deenergizes since contact 73 is ungrounded before contact 58 becomes closed, and since contact 80 is open, no circuit for winding 10 is completed and no long step of the wipers is produced. The relay SR was operated as before by the closure of contact 83-8 l and for the proper operation of switch F, must continue operated when relay PR deenergizes to close circuit at contact 83 for the locking relay 89, so that the short- "step, travel of line selector E may be initiated by current from generator 9 passing through contacts 5 and 102. In. this particular situation, attracted armature 87 of relay 85 keeps the circuit closed from ground through normal contact 19, wiper G3,'-attracted armature 101, normal contact 84, and

contact 83-84 opens normal contact 97 and the relay SR. Relay 8.) now operates. by current through closed contact 88 and normal contact 83, and the selection of the indiswitches on a second revolution.

vidual contacts of the calling as before.

Referring to first selector F, second selector G and connector H, it will be seen that if contacts in their tenth groups are to be selected, ten long steps of the wipers will be produced so that they will be brought around to normal and the travel to select idle contacts in the tenth group will start the In such cases, the restorations to normal will be accomplished by causing the switches to complete a second revolution. Referring to the first selector F, the tenth step of the first selector will, at its conclusion, leave the oil? normal contact 17-11; 0p91'l, the secondary inipulse will operate "the relay LE as before, which will lock to ground through the tenth lino proceeds contact of ring 1&5, operating the relay BB as before. The operation of that relay, by closing contact 162, does not instantly actuthe relay PR will ate the locking relay LR, as in the previous but a first short stop of the description, switch wipers is produced as before, contact 174 is closed, and locking relay LR then operates instantly, the remaining operations being as before.

In. the second selector G, the operation of selecting idle contacts of the tenth group is similar to the operation described for the selector l relays LE Bit and LR corresponding to the relays LR, BB and LR of first selector F, and contact 211 corresponding to contact 174.

In the connector H, there are no essential dili erences in the method of operatioi'i when contacts or" the tenth group are selected. At the conclusion of the tenth step, the oil'- normal contact 225 will, of course, be opened, but relay LR" will remain energized via closed contact 229 of relay LE and accordingly stop-magnet 14 will he energized by Way of contact 224 as before, and the subsequent impulses will give the shortstep travel to the desired contacts. And in the case of release, circuit is completed through contact 200-4201, wire 208, normal contact 244:, (the relay 213 having, of course, remained unoperated,) and through the upper winding of relay HR to ground via T he relay RR, by armature 23S, locks itself to ground zit-attracted armature 22$ before, and the release of-the connector 11 pro ceeds in a manner which will be understood from the preceding description.

Figs. 2 and 8 show circuits adapted to be employed in the place of Fig. 1, part 2, and 1, part 3, respectively, of the complete circuit diagram previously described. The second complete diagram would therefore include Fig. 1, part 1, at the left, Figs. 2 and 3, and Fig. l, part4, placed side by side consecutively. The first selector F and second selector G are quite similar to the first selector F and second selector G respew tively, but provision is made in F and G whereby the use of the contacts 152 and 200 is avoided. In a system operating in accordance with this second complete diagram, the operation of the line selector and of the relays PR and SH of first selector h" is the same as in the previous case, including the control of said relays from the substation.

Assuming the same number is to be selected, the deeuergization of relay llt transmits an lll'll'flllia'G from ground through contacts 118, 116, through contact 120 and long step winding 10*, producing a long step as before. The current, after passing through contact 126 in the present case, divides, a portion flowing through normal contacts 13(3 and 132 to operate. locking relay LR which, at the conclusion of the impulse, will, by armature 13], be held locked through contact144-1l5 at 7). Thereafter the impulse transmitted by the denergization of relay SR passes through contacts 117, 119, attracted armature 135, relay BR, and stop magnet 14 to battery operating said magnet. The attraction of armature 139 of re lay BR energizes the locking relay LR which, by armature 129, looks to ground at oft-normal contact 120. The circuit for the short-step winding 10 is now closed through contacts 5, 127, and alternate contact 137. On the resulting first short step of the switch wipers, relay LR is unlocked and deiinergized by opening of contact 144145 at Z), and a previously existing locking circuit for magnet 14 and relay BR, extending through attracted armature 138 and closed contact 133134, is opened, and the make-beforebreak spring 133 shifts the circuit of magnet 14 and relay BR via contacts 143 and normal contact 124 to the private wiper 146. The relay BR and magnet 14 of course remain operated until wiper 146 reaches an idle or ungrounded contact 147 when circuit through them will he opened and their deenergization will prevent further steps of the switch. The retraction of armature 137 in the present case operates the relay 121 by current through closed contact 128 and the connection is extended to the talking wipers 148, 150. In releasing the first selector F, the battery impulse istransmitted as before over wire 110, the current traversing alternate contacts 124, 123, release relay RR, passing to ground through alternate contact 130. Armature 142 of relay RR operates busy relay RR and stop magnet 14 in series, and short-stop travel of the first selector F is completed around to normal in an obvious manner, at which time the opening of contact 120 will deenergize the relay L11 whose armature 130 opens the locking circuit for relay RR and the de'e'nergization of this relay, by opening contact 142, of course deenergizes the relay BR and the stop magnet 14*. ()n the cnergization of relay BR, at initiation of the release, the opening of normal contact 137 de'e'nergizcd the relay 121 so that the first selector F is now at normal.

Referring to Fig. 3, the operation of the second selector G there shown is substantially like that of the first selector F. The transmission of the first impulse over wire 177 operates long step winding 10 and the locking relay LR, which, by armature 267,

locks to ground through the contact 198 i 19-) at Z). The secondary impulse over wire 178 passes through contact 271, relay BR and magnet 14 operating the same, whereon '1 armature 275 of relay BR energizes the locking relay LR which looks to ground at off-normal contact 261. The short-step travel of the switch is now produced by current from generator 9 through winding 10",

281 and release relay RR to ground at alter- I na-te contact 266. The operation of release relay RR, by armature 278, operates in series, relay BR and magnet 14*, and shortstop travel of the second selector G is produced until the wipers reach normal, when theopening of off-normal contact 261 initiates circuit changes, placing the mechanism of the second selector at normal, which occurs in an obvious manner.

The operation of the connector H, when employed in connection with the circuits of Figs. 2 and 3, differs in no respect from that in which it was operated when employed in the first circuit diagram.

While I have shown in the circuit dia: grams the conductors of the various selector switches as connected directly to wiper contacts for the sake of securing greater simplicity in the diagrams, I prefer in practice to terminate the conductors, shown as terminating in wipers in the diagrams, in stationary contacts in the mechanical switches, forming what are called common strips, which are preferably of circular form. The contacts, to which these common strips are to be connected, are placed adjacent to them, respectively, and the switch wipers mounted upon the shaft have in themselves no circuit connections, serving merely to cross the respective commons to their associated contacts. In Fig. 5, the strips63, 64, 65, 66 represent the corresponding wiper contacts shown in Fig. 1, part 1, the wipers m,

n, 0 and p, with the travel of the switch, operate to close the commons 63, 64, 65, 6,6 to their respective associated contacts. The wiper s has associated with it the off-normal contacts 697O and 67-68. When the switch leaves normal, the wiper s disengages'the contacts 69, 70, thus opening circuit between them; and on the firststep, it engages the contacts 67, 68, making a bridged connection between them, thus producing the closed circuit condition requlred by the circuit-diagram of Fig. 1, part 1. In Figs. 7 8, 9 and 10, are given .views illustrating the common conductors for the line selector E, their associated contacts and the manner in which 

